ViewController 将 Swift 从一个 VC 推送到另一个 VC 并返回

Question

考虑两个视图控制器 Controller1 和 Controller2，我在控制器 1 中创建了许多 UITextField 的表单，当用户单击特定的 UITextField 时，它会移动到 Controller2 并选择那里的数据.

选择Controller2中的数据后，它会自动移动到Controller1，而从控制器2返回控制器1时，其他UITextfield数据被清除，只找到控制器2中选择的数据。选择后我需要在UITextfield 中找到所有数据。

这是从Controller2返回到Controller1的代码

 if(Constants.SelectedComplexName != nil)
  {
      let storyBoard: UIStoryboard = UIStoryboard(name: "NewUserLogin", bundle: nil)
      let newViewController = storyBoard.instantiateViewController(withIdentifier: "NewUser") as! NewUserRegistrationViewController
      self.present(newViewController, animated: true, completion: nil)
   }

Answer 1

要传递消息，您需要实现Delegate。

protocol SecondViewControllerDelegate: NSObjectProtocol {
    func didUpdateData(controller: SecondViewController, data: YourDataModel)
}
//This is your Data Model and suppose it contain 'name', 'email', 'phoneNumber'
class YourDataModel: NSObject {
    var name: String? //
    var phoneNumber: String?
    var email: String?
}
class FirstViewController: UIViewController, SecondViewControllerDelegate {
    var data: YourDataModel?
    var nameTextField: UITextField?
    var phoneNumberTextField: UITextField?
    var emailTextField: UITextField?

    override func viewDidLoad() {
        super.viewDidLoad()
        callWebApi()
    }

    func callWebApi() {
        //After Success Fully Getting Data From Api
        //Set this data to your global object and then call setDataToTextField()
        //self.data = apiResponseData
        self.setDataToTextField()
    }

    func setDataToTextField() {
        self.nameTextField?.text = data?.name
        self.phoneNumberTextField?.text = data?.phoneNumber
        self.emailTextField?.text = data?.email
    }

    func openNextScreen() {
        let vc2 = SecondViewController()//Or initialize it from storyboard.instantiate method
        vc2.delegate = self//tell second vc to call didUpdateData of this class.
        self.navigationController?.pushViewController(vc2, animated: true)
    }

    //This didUpdateData method will call automatically from second view controller when the data is change
    func didUpdateData(controller: SecondViewController, data: YourDataModel) {

    }
}
class SecondViewController: UIViewController {
    var delegate: SecondViewControllerDelegate?

    func setThisData(d: YourDataModel) {
        self.navigationController?.popViewController(animated: true)
        //Right After Going Back tell your previous screen that data is updated.
        //To do this you need to call didUpdate method from the delegate object.
        if let del = self.delegate {
            del.didUpdateData(controller: self, data: d)
        }
    }
}

Answer 2

push your view controller instead of a present like this  


if(Constants.SelectedComplexName != nil)
 {
    let storyBoard: UIStoryboard = UIStoryboard(name: "NewUserLogin", bundle: nil)
    let newViewController = storyBoard.instantiateViewController(withIdentifier: "NewUser") as! NewUserRegistrationViewController
    self.navigationController?.pushViewController(newViewController, animated: true)
 }

然后像这样从vc2中选择数据后弹出

self.navigationController?.popViewController(animated: true)

如果你不使用导航控制器，那么你可以简单地调用Dismiss方法

self.dismiss(animated: true) {
    print("updaae your data")
}

Answer 3

有几种方法可以做到这一点，但这通常取决于您如何从 VC#1 移动到 VC#2 并返回。

(1) 您发布的代码意味着您有一个带有两个视图控制器的故事板。在这种情况下，创建从 VC#1 到 VC#2 的转场和“展开”转场。两者都相当容易做到。 cmets 中提供的link 可以很好地向您展示，但是，取决于 (1) 您希望将多少数据传回 VC#1 和 (2) 如果您希望在 VC#2 上执行函数，你也可以这样做：

VC#1：

override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
    if segue.identifier == "ShowVC2" {
        if let vc = segue.destination as? VC2ViewController {
            vc.VC1 = self
        }
    }
}

VC#2：

weak var VC1:VC1ViewController!

override func viewWillDisappear(_ animated: Bool) {
    super.viewWillDisappear(animated)
    if isMovingFromParentViewController {
        VC1.executeSomeFunction()
    }
}

基本上，您传递的是 VC1 的 整个 实例，因此可以访问未标记为 private 的所有内容。

(2) 如果您要从 VC#1 呈现/关闭 VC#2，请使用答案之一所述的 delegate 样式。

VC#1：

var VC2 = VC2ViewController()

extension VC1ViewController: VC2ControlllerDelegate {
    func showVC2() {
        VC2.delegate = self
        VC2.someData = someData
        present(VC2, animated: true, completion: nil)
    }
    function somethingChanged(sender: VC2ViewController) {
        // you'll find your data in sender.someData, do what you need
    }
}

VC#2：

protocol VC2Delegate {
    func somethingChanged(sender: VC2ViewController) {
        delegate.somethingChanged(sender: self)
    }
}
class DefineViewController: UIViewController {

    var delegate:DefineVCDelegate! = nil
    var someData:Any!

    func dismissMe() {
        delegate.somethingChanged(sender: self)
        dismiss(animated: true, completion: nil)
    }
}

}

基本上，您让 VC#1 成为 VC2 的代表。我更喜欢 VC#2 中 `delegate 的声明语法，因为如果您忘记将 VC#1 设置为 VC#2 的委托，您的测试将在运行时强制出错。